Walk-in coolers and freezers

In North America, these systems are widely used in grocery retail, food service, processing, and distribution, where uptime, reliable temperature control, and compliance with U.S. safety, environmental, and refrigerant regulations are critical. 

Danfoss supports walk-in cooler and freezer installations with refrigeration components, refrigerant‑ready solutions, and digital selection tools that help contractors choose compatible products, simplify installation, and plan for low‑GWP and natural refrigerants.   

On this page you can: 

• Understand the main components of a walk-in cooler and freezer system  
• Compare refrigerant-ready solution paths  
• See where Danfoss products fit in a typical installation  
• Use tools to size and select the right components  
• Get answers to common contractor questions 

How a walk-in cooler and freezer refrigeration system works? 

A walk-in cooler and freezer refrigeration system removes heat from an enclosed space to keep products at a stable, controlled temperature. It works by circulating refrigerant through a closed loop of components that compress, condense, expand, and evaporate the refrigerant, while controllers continuously monitor and regulate operating conditions. 

Walk-in systems are designed to run continuously, which makes component compatibility, control logic, and refrigerant choice critical for system performance, energy efficiency, and lifetime. 

Core components in a typical walk-in cooler and freezer refrigeration system

A typical walk-in cooler and freezer refrigeration system includes these main component groups, each with a specific role in reliable operation:

• Condensing unit – provides the refrigeration capacity and rejects heat 
• Compressor – compresses and circulates the refrigerant and is an integrated part of the condensing unit  
• Walk-in cooler and freezer controller – regulates temperature, defrost, alarms, and protection 
• Thermostatic expansion valve (TXV) – controls refrigerant flow into the evaporator 
• Solenoid valve – enables refrigerant control and shut‑off functions (e.g. pump down operation) 
• Filter drier – removes moisture and contaminants to protect the system 
• Evaporator – transfers heat from the room air to the refrigerant 

What matters most when selecting walk-in cooler and freezer components?

Walk-in cooler and freezer refrigeration system components: function and examples

Why system integration matters

In walk-in cooler and freezer applications, reliability depends on how well components work together as a system, not only on individual product performance. Correct matching of compressors, valves, cooler and freezer controllers, and refrigerants helps ensure: 

• Stable room temperatures 
• Efficient operation and lower energy consumption 
• Compliance with refrigerant regulations 
• Longer system lifetime and easier servicing 

Danfoss supports this system‑level approach by offering compatible component portfolios, refrigerant‑ready solutions, and digital selection tools that help contractors design and build walk-in cooler and freezer systems with confidence.

Which walk-in cooler and freezer solution should you choose?

Choosing the right walk-in cooler and freezer solution starts with understanding the application goal, the refrigerant strategy, and the level of control and efficiency required. The guide below helps technicians decide what to start with and what to check next before final selection.

Decision guide: contractor goals vs solution path

When selecting a walk-in solution, technicians typically start with the application type and refrigerant strategy, then confirm component compatibility, control requirements, and efficiency targets before finalizing selection. 

Refrigerant options for walk-in cooler and freezer applications

Walk-in cooler and freezer projects typically choose between A1 retrofit, A2L transition, CO₂, hydrocarbons like propane (R290) where applicable. A2L is used when low-GWP is required with a practical transition path, while CO₂ is chosen for its very low GWP and non-flammability. Hydrocarbons like propane (R290) are another very low GWP potential option when relevant safety aspects and requirements due to their high flammability are taken into consideration.  

Refrigerant choice affects efficiency, regulatory compliance, safety requirements, and long‑term system viability.
This overview helps identify which refrigerant path best fits your cooler and freezer application before you explore detailed solution pages.

Which refrigerant path is right for my walk-in cooler and freezer? 

Most projects follow one of four paths: A1 (legacy/retrofit), A2L (transition), CO₂ (non-flammable and very-low GWP), or R290 propane (where applicable for self-contained/compact systems). Your best fit depends on whether you are retrofitting or planning for new, very low GWP refrigeration system installations. 

When should I choose CO₂ (R744) for a walk-in cooler and freezer? 

Choose CO₂ when the project prioritizes a non-flammable pathway and very low GWP. CO₂ systems operate at significantly higher pressures than traditional HFC systems, requiring components and designs suited for high-pressure applications, so component selection and system design differ from many legacy systems. 

Best fit for: Commercial walk-in cooler and freezers prioritizing non-flammability and long‑term sustainability targets.

Use CO₂ when you need: 

• Very low GWP 
• A non-flammablility pathway 
• Solutions aligned with future regulatory and sustainability strategies 

If you choose CO₂ refrigerant

The resources below help you answer questions such as: 

• Is CO₂ suitable for this cold room size and temperature? 
• Which control and valve strategy is required? 
• How do I select components for high‑pressure operation? 

When should I choose A2L refrigerants for a walk-in cooler and freezer? 

Choose an A2L refrigerant when you need low-GWP than legacy HFC solutions and want a practical transition option for selected cooler and freezer systems. A2L projects typically require planning around component compatibility, charge limits, and safety requirements. 

Best fit for: New systems or selected retrofits that require lower GWP with a practical transition approach. 
 
Use A2L when you need: 

• Lower GWP than legacy HFC solutions 
• A transition path aligned with evolving regulations 
• Compatibility planning across components, charge limits, and safety requirements 
   

If you choose A2L refrigerant 

The resources below help you answer questions such as: 

• Which components require A2L compatibility? 
• What safety requirements and charge limits apply? 
• How do I plan system architecture for A2L refrigerants? 

When should I choose A1 (legacy / non‑flammable retrofit path)? 

Choose an A1 retrofit path when the priority is continuity of an existing system, and a refrigerant change is not feasible in the short term. Plan for future transition if regulations or supply constraints tighten. 

Best fit for: Installed-base continuity and short‑term retrofit practicality. 

Next step: confirm compatibility and plan a staged transition 

When is propane (R290) relevant for walk-in cooler and freezers? 

Choose a propane refrigerant when the project uses compact or self-contained concepts where propane is applicable, and safety requirements can be met. Propane is a hydrocarbon refrigerant with very low GWP, but system design must follow relevant safety requirements and charge considerations. 

Best fit for: Smaller/self-contained solutions where applicable.

Use these documents when you need a deeper reference during system selection, design review, or installation. 

What’s new in the world of walk-in cooler and freezer solutions?

Stay updated on Danfoss product news relevant to:

• superheat control 
• valve developments 
• controller updates 
• refrigerant-ready component ranges

Need help with a walk-in cooler and freezer project? 

Talk to Danfoss if you need support with: 

• component selection 
• refrigerant transition planning 
• control strategy 
• technical documentation 
• product compatibility

What components are needed for a walk-in cooler and freezer refrigeration system? 

A typical system includes a condensing unit, compressor, controller, expansion valve, solenoid valve, filter drier, and evaporator. Danfoss supports this system architecture with products such as Optyma™ condensing units, Optyma™ cold room controller, thermostatic expansion valves, solenoid valves, filter driers, and refrigeration compressors.

Which controller is used for walk-in cooler and freezer temperature management? 

For many walk-in cooler and freezer applications, technicians use a dedicated walk-in cooler and freezer controller that manages temperature, defrost, alarms, and connected components. Danfoss positions Optyma™ Control as a walk-in cooler and freezer controller designed for safety, protection, and ease of installation. 

Which valve is used to control refrigerant flow into the evaporator? 

A thermostatic expansion valve controls refrigerant injection into the evaporator and helps maintain stable superheat. Danfoss thermostatic expansion valve product ranges are designed for refrigeration applications and long service life. 

Why is a filter drier important in a walk-in cooler and freezer system? 

A filter drier helps protect the refrigeration system from moisture, acids, and solid particles that can reduce reliability and compressor life. Danfoss DML/DCL filter driers are designed for this protection function. 

Which refrigerant should I choose for a walk-in cooler and freezer? 

That depends on the application, regulatory context, safety requirements, and long-term refrigerant strategy. Danfoss provides content and products across low-GWP, A2L, and CO₂ pathways.

What walk-in cooler do I need for a small restaurant?

Choose a cooler sized for 300–400 cu ft, 35–38°F, matching daily storage and peak load.

Best condensing unit for a commercial walk-in freezer?

Select a low-temp unit with adequate BTU/hr for freezer load, e.g., Danfoss Optyma™ Plus for -10°F.

How do I size a refrigeration system for a walk-in cooler, and does the refrigerant choice change what equipment I need?

Calculate heat load from product, infiltration, and ambient, then match BTU/hr to compressor capacity.

My walk-in cooler compressor runs all day but it's not getting cold enough. How do I figure out what's wrong?

Check door seals, condenser coil cleanliness, evaporator airflow, and thermostat settings. Verify equipment capacity matches load and check super heat and subcooling to ensure proper refrigerant charge.

A2L refrigerant options for commercial walk-in coolers in the US?

R454A, R455A, and R1234yf are EPA SNAP-approved A2L options for walk-in coolers. For retrofits, verify compatibility with existing components including capacity changes and TXV superheat changes.

What do I need to build a walk-in cooler from scratch with A2L refrigerant — and are there extra safety components required by the AIM Act?

Panels, door, condensing unit, evaporator, piping, expansion valve, controller, and lighting.

What expansion valve do I need for a walk-in freezer, and should I go with a thermostatic or electronic valve?

Use a thermostatic expansion valve sized for low-temp load and refrigerant type, e.g., Danfoss TE5 or TU series. Do not use nominal capacity of TXV when matching evaporator capacity.

CO₂ vs HFC systems for supermarket cold rooms — cost comparison?

CO₂ has higher initial cost but lower long-term refrigerant cost; HFC is cheaper upfront but faces phase-down.

How do I retrofit a walk-in cooler from R404A to a low-GWP refrigerant?

Replace seals, check oil compatibility, adjust expansion valve, and recharge with approved low-GWP refrigerant. Check to make sure that super heat adjusment alond will be sufficient to adjust for the changs. If not, a dedicated TXV for that refrigerant will be necessary. 

What controller should I use for a commercial walk-in cooler?

Use an electronic controller with temperature, defrost, and alarm functions, e.g., Danfoss ERC series.

Best cold room setup for meat processing facility?

Maintain 32–35°F with humidity control, stainless steel surfaces, and robust airflow for even cooling.

Energy-efficient refrigeration for grocery store walk-in coolers?

Use high-efficiency compressors, EC fans, LED lighting, and demand-based defrost cycles. Utilize floating head pressure if condensers are outside.

What are the safety requirements for A2L refrigerants in a commercial kitchen?

Ensure leak detection, ventilation, charge limits, and compliance with ASHRAE 15.

What are the commissioning steps after installing a new walk-in cooler — what do I need to check before handing it over?

Verify components match capacity wise for proper balance. Verify pressure tests, vacuum, refrigerant charge, controller settings, and temperature stability. Ensure proper voltage with compressors running and verify discharge temperature is within manufacturers specifications. 

Which condensing unit brands are most reliable for walk-in coolers?

Danfoss is widely trusted for reliability in US commercial applications. Proper installation and start up are just as important as brand.

What components do I need for a small dairy plant that needs both a chilled room and a freezer — can I run them off the same system?

Insulated panels, hygienic flooring, condensing unit, evaporator, humidity control, and wash-down lighting.

What temperature and humidity controls are required for meat aging rooms?

Maintain 32–35°F and 75–85% RH with precise control to prevent spoilage and ensure quality. 

How do I design a blast chiller for a food production facility — what kind of cooling capacity and condensing unit do I need to pull down temperature fast?

Size for rapid pull-down to ≤39°F within 90 minutes, with high airflow and robust insulation.

Walk-in cooler for a hotel kitchen — what size and type do I need?

Choose 350–500 cu ft, 35–38°F, with shelving for varied products and easy access for staff.

Best refrigeration setup for a restaurant with both walk-in cooler and walk-in freezer?

Use separate condensing units and evaporators to optimize temperature control and efficiency. Ensure proper heat rejection from both the units and the space if condensing units are located indoors.

What's the best walk-in cooler configuration for a grocery store with high foot traffic?

Place cooler near prep area with double doors, fast-closing mechanisms, and high-capacity airflow.

Should I put one big walk-in cooler or several smaller ones in a convenience store — what's better for energy costs and maintenance?

Multiple smaller units improve temperature control and reduce cross-contamination risk.

What's the best way to cut energy costs across multiple walk-in coolers in a supermarket — better controls, smarter defrost, or new equipment?

Install variable-speed compressors, optimize defrost schedules, and improve door sealing.

My walk-in cooler can't hold temperature even though the compressor never stops. How do I figure out if it's undersized, leaking, or a controls problem?

Check for refrigerant leaks, dirty coils, poor airflow, or faulty thermostat. Verify system and component capacities match load requirements. Check refrigerant charge to ensure it is adequate.

How often should I schedule preventive maintenance on commercial walk-in coolers?

Every 3–6 months for cleaning, inspection, and performance checks.

What monitoring system can alert me if a walk-in cooler temperature goes out of range?

Use a remote monitoring system with SMS/email alerts, e.g., Danfoss AKC series.

My walk-in cooler is 15 years old. Should I upgrade the components or replace the whole thing — and do refrigerant phase-out rules force my hand?

Replace if insulation, compressor, or panels are degraded; upgrade if only controls or fans need improvement.

What should I look for when comparing walk-in cooler quotes from contractors?

Compare insulation quality, compressor efficiency, warranty terms, and installation costs.

What does a walk-in cooler actually cost to own over 10 years — and how do the long-term costs compare between R404A, A2L, and CO₂?

Include energy use, maintenance, repairs, and refrigerant costs over lifespan.

Which walk-in cooler components have the longest warranty and lowest failure rates?

Compressors and panels often have longest warranties; EC fans and LED lights have low failure rates.

Temperature mapping and validation for a pharmaceutical walk-in cooler — what's required?

Map multiple points, verify uniformity, and document compliance with FDA GDP guidelines.

What controller and alarm setup do I need for a vaccine storage walk-in cooler?

Use a dual-sensor controller with high/low alarms and backup power supply.

How do I get the refrigerant charge right for a walk-in cooler, and what happens if I put in too much or too little with A2L?

Use manufacturer’s guidelines based on pipe length, evaporator, and condenser volume. Verify with subcooling comparing to manufacturers specifications. 

What pipe sizing guidelines apply to a walk-in cooler refrigeration system?

Follow refrigerant-specific velocity and pressure drop limits per ASHRAE standards.

How do I select an electronic expansion valve vs a thermostatic valve for a walk-in cooler?

Choose EEV for precise control and variable load; TEV for simpler, fixed-load systems.

My walk-in freezer keeps icing up even though the defrost runs. How do I figure out what's causing it?

Check defrost cycle, door seals, and humidity infiltration.

How do I check and adjust superheat on a walk-in cooler TXV, and how do I know if it's set wrong?

Adjust stem until measured superheat matches manufacturer’s recommended value.

After putting in a new compressor, my walk-in cooler keeps tripping on high pressure. What should I check first?

Inspect condenser airflow, refrigerant charge, and pressure control settings.

Where's the best place to put a condensing unit for a walk-in cooler — rooftop, ground level, or inside? What are the trade-offs?

Place in shaded, ventilated area with easy service access and minimal pipe run.

What do I need to know about running refrigerant lines through a building to a walk-in cooler — how long can they be, and what are the rules?

Use shortest route possible, support lines, and insulate suction lines.

What refrigerant strategy should a supermarket chain adopt as R404A is phased out?

Transition to low-GWP refrigerants like CO₂ or A2L blends, considering retrofit feasibility.

How do CO₂ transcritical systems compare to A2L systems for commercial walk-in coolers in the US?

CO₂ offers zero GWP but higher complexity; A2L blends are simpler retrofits with lower GWP.

What are A2L refrigerants and why is the industry switching to them?

A2L refrigerants are mildly flammable, low-GWP alternatives to HFCs, meeting regulatory phase-down goals.